Food container having improved tamper evident features

ABSTRACT

A plastic food container includes a lid adapted for sealing arrangement with a base. The rim of the base has an undercut formation adapted to receive the perimeter flange and flange tab of the lid when the lid and base are in the sealed arrangement. The flange tab includes an undercut release mechanism that allows a user to grasp a portion of the flange tab and initially open a sealed container via the extraction of the flange tab from the undercut formation by application of pulling force to the undercut release mechanism. The flange tab includes tamper evident means that provides visible indication that the undercut release mechanism has been utilized to initially open the sealed container.

CROSS REFERENCE TO RELATED APPLICATION

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM ON COMPACT DISC

Not applicable.

FIELD OF INVENTION

This invention relates generally to plastic food containers. The invention is more specifically related to resealable plastic food containers having tamper evident sealing mechanisms.

BACKGROUND OF THE INVENTION

It is known to use plastic containers in the food preparation and restaurant industry to package prepared foods. The typical food container of the prior art consists of a solid color (typically black) base and a clear lid. The clear lid of the prior art plastic food container allows visible inspection of the container contents. The lid and base of the prior art plastic food container may be separate articles or may be hingedly attached to each other.

In order to maintain the quality of food contents and prevent tampering with the contents of a sealed container, it is desirable that the food container, once sealed, not be capable of being initially opened without visible indication of the container having been opened. Accordingly, it is known in the prior art to manufacture food containers having tamper evident sealing mechanisms. In this regard, the prior art plastic food container has utilized a band of tape around the sealed container or a sticker label extending across a portion of the contact area of lid and base rims of the sealed container for tamper evidence. Opening the container (i.e., separating the lid from the base) requires rupturing the band or sticker label. The ruptured band or label provides evidence of tampering or initial opening of the sealed container. A problem with this method of tamper evidence is that the container requires articles apart from the container itself to effect the tamper evidence. In addition, to make the container tamper evident, the additional step of applying the band or label is required after sealing the container.

To address the above problem, container manufacturers have designed containers having integral tamper evident features. Typically, these containers consist of a lid that is hingedly attached to a base. The lid seals to the base by superposing the rim of the lid upon the rim of the base. The lid and base each have interlocking elements respectively located on or near the lid rim and base rim. The interlocking element of the lid or base is conventionally located on a tab or flange extending from the rim of the lid or base. Either or both of the tabs are attached to their respective rims by a frangible section of plastic. When the lid and base are placed in sealing arrangement, the interlocking elements on or near the lid rim and base rim engage and lock together. In order to open the sealed container, the frangible section of one or both tabs must be ruptured so as to release the tab or tabs from the container. Because the interlocking sealing elements are located on the tabs, rupturing one or more tabs from the container, disables the locking mechanism. The ruptured tab provides evidence of the container having been opened.

One shortcoming with the prior art food container relying on interlocking elements located upon a outer frangible tab is that the interlocked tabs can be cut from the container in clean fashion using scissors or another cutting implement so as to remove any indicia of the container having had a tamper evident mechanism. Another shortcoming involves the additional plastic required to manufacture the tabs. Still another problem with the prior art tamper evident food container arises from the sealing arrangement of the container rims. As noted, in the prior art container one rim (typically the lid rim) superposes over the other rim (typically the base rim) such that at least one of the rim edges is exposed. With this type of sealing arrangement and construct in plastic containers, the lid and base can be partially pried open by inserting a thin object underneath an exposed rim edge at a point on the container distal from the tamper indicator. By partially prying open the rims in this fashion, one can doctor or tamper with the contents of the apparently sealed container without activating the tamper indicator.

There is thus a need in the art for a reclosable plastic food container that is easy for end consumers to operate; combines reliable tamper evidence and defense against prying intrusion; and that uses a minimum of material to manufacture.

SUMMARY OF THE INVENTION

The present invention satisfies the needs in the art and provides an aesthetically appealing food container that is easy to use and that is both tamper resistant and tamper evident. In this respect the present invention food container comprises a plastic food container having a lid adapted for sealing arrangement with a base. The lid has a perimeter flange that includes at least one localized, integrally formed flange tab. The base has a floor and a rim and a sidewall extending between the floor and the rim. The rim of the base has an undercut formation. The undercut formation is adapted to receive the perimeter flange and flange tab when the lid and base are in the sealed arrangement. The flange tab includes an undercut release mechanism, which allows a portion of the flange tab to be grasped and pulled. Pulling the flange tab extracts its edge from the undercut formation of the base rim. The undercut release mechanism is formed such that the pulling force necessary to extract the flange tab from the undercut formation deforms the flange tab. The deformed flange tab provides visible evidence that the sealed container has been initially opened.

More specifically, the container comprises a lid adapted for sealing arrangement with a base. The lid comprises an upper portion, a descending surface and a rim that engages the rim of the base. In a preferred embodiment and as viewed from a cross section aspect, the upper portion of the lid comprises one or more horizontal and vertical surfaces that extend to form the descending surface. The descending surface extends to form a horizontal transition segment. This segment descends to form a multi-segment rim structure. This rim structure includes a generally vertically oriented inner wall. The inner wall curves outwardly (peripherally) to form a peripherally projecting segment that defines the lowermost point of the lid.

The respective rims of the lid and base each have a complementary engaging multi-surface (segment) structure. In this regard, the lid rim structure includes a vertical sealing segment that extends upwardly from the peripherally projecting segment to a perimeter flange. The lid vertical sealing segment is angled inwardly (towards the interior of container).

In addition to having a complementary rim with multi-segment structure, the base comprises a floor and a sidewall, the sidewall extending between the floor and the rim. The base rim structure contains an undercut formation that is adapted to engage the perimeter flange of the lid. The method by which the lid is retained by the undercut formation of the base rim provides defense against access to the sealed container contents via prying of the lid from the base.

The perimeter flange of the lid includes at least one integrally formed flange tab, which when the container is sealed is also protectively captured by the undercut structure of the base rim. This flange tab is generally planar and incorporates an undercut release mechanism that allows a user to extract the engaged flange tab from the base rim. In the preferred embodiment, the undercut release mechanism is a releasable grip tab integrally formed in the flange tab via a frangible outline of perforations or scoring. The perforations or scoring define the shape of the grip tab. By providing the container with these features, a three-step process is required to open the container. First, a separation force must be applied to the grip tab to cause rupture of its frangible outline and the grip tab to pop up out of the flange tab to a position it can be grasped by a thumb and forefinger. Second, the now released grip tab is pulled toward the user, causing the engaged flange tab to roll inwardly down and be released by the base rim structure. Third, once the flange tab is disengaged from the base rim structure, the lid can be removed from the base by pulling the flange tab up and inwardly toward the center of the container. This last pulling action causes the disengagement of the lid perimeter flange from the base rim.

The undercut release mechanism is further adapted to deform when tab-releasing forces are applied to it. This deformation provides visible indication that the container has been initially opened. In this regard, the flange tab includes a fracture line that prefereably emanates from the frangible outline defining the grip tab. This fracture line is designed to rupture when pulling action is imparted to the grip tab to extract the flange tab from the base rim's undercut formation. The rupturing of this fracture line provides visible indication that the grip tab has been employed to open the container. In addition, the undercut release mechanism is designed such that once the fracture line ruptures, the application of pulling force to the grip tab or flange tab will cause further visible deformation of the flange tab from its original planar shape. This deformation provides additional indicia that the lid retaining mechanism of the container has been compromised and that the lid has been subjected to opening forces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of the present invention container in the sealed arrangement.

FIG. 2 is a side elevation view of the preferred embodiment present invention container in the sealed arrangement.

FIG. 3 is a perspective view of the base of the preferred embodiment present invention container.

FIG. 4 is a cross-section view taken along line A-A of FIG. 1.

FIG. 5 is a cross-section view taken along line B-B of FIG. 3.

FIG. 6 is more detailed view of circumscribed area Z of FIG. 5 showing the multi-segment rim structure of the base of the preferred embodiment present invention container.

FIG. 7 is a plan view of the lid of the present invention container having a preferred embodiment tamper evident flange tab.

FIG. 8 is a cross section view of the rim structure of the lid of the preferred embodiment present invention container taken along line C-C of FIG. 7.

FIG. 9 is a detailed view of circumscribed area Y of FIG. 4 showing the mechanics of engagement between the lid rim structure and base rim structure when the container is sealed.

FIG. 10 is a cross section view taken along line D-D of FIG. 7 and showing the profile of a preferred embodiment lid tab.

FIG. 11 is a cross section view taken along line E-E of FIG. 1 and showing the mechanics of engagement between the flange tab and the base rim structure when the container is sealed.

FIG. 12 is a perspective view of the tamper evident flange tab showing the grip tab deployed and ready to be pulled to open the container.

FIG. 13 is a perspective view of the tamper evident flange tab showing example deformation of the flange tab after the container has been opened through use of the grip tab.

FIGS. 14 a-d are plan views of alternate embodiment flange tabs having differently configured fracture lines designed to enhance tamper evidence.

FIG. 15 is an exploded perspective view of a lid flange tab and base platform having a simpler grip tab construct designed to be deployed via the application of upwardly directed finger pressure through a hole in the platform.

DETAILED DESCRIPTION

A preferred embodiment container 10 of the present invention in the sealed arrangement is shown in FIGS. 1 and 4. As shown by these figures container 10 is composed of lid 11 and base 25. Lid 11 includes upper portion 12, descending surface 13 and multi-segment rim 14. Lid 11 is manufactured from a conventional plastic material and is clear. Upper portion 12 is preferably flat, but can be contoured and ribbed in accordance with the prior art to enhance such factors as container volume, strength, nesting of multiple lids, stackability of sealed containers and see-through visibility. In the preferred embodiment lid upper portion 12 includes top plateau 15 and intermediate terrace 16. First lid transition segment 17 extends between plateau 15 and terrace 16. Terrace 16 continues on to form second vertical transition segment 18. Vertical transitional section 18 provides structural rigidity to lid 11 and extends from terrace 16 to descending surface 13, which in the preferred embodiment is an arcuate segment with its concave surface directed toward the interior of container 11. Third (horizontal) lid transition segment 23 extends between descending surface 13 and inner wall 19 of lid rim structure 14 and provides structural rigidity to lid 11. Lid 11 is shaped so as not to allow a finger-hold on the lid once the lid is in sealing arrangement with the base.

The structure of lid rim 14 will now be discussed in further detail. As best shown in FIGS. 4, 7, 8 and 9, lid rim 14 includes peripherally projecting segment 20, which extends between inner wall 19 and lid vertical sealing segment 21. The cross-section profile of segment 20 is generally horizontal. The profile, however, can be shaped to include structure such as ribbing, curves or bends to modulate rim rigidity or flexibility so as to enhance the closing, sealing and opening functions of the rim as needed. The drawings depict a preferred embodiment cross-section profile of this peripherally projecting segment. Lid vertical sealing segment 21 extends upwardly between peripherally projecting segment 20 and peripheral flange 22. Lid vertical sealing segment 21 is preferably angled inwardly (towards the interior of container 10).

The structure of base 25 and its rim structure 30 is best shown in FIGS. 3, 5, 6 and 9. Base 25 includes floor 31 adjoined to sidewall 32. Sidewall 32 extends between base floor 31 and multi-segment rim 30. The structure of base rim 30 is adapted to complementarily engage the structure of lid rim 14 when lid 11 and base 25 are placed in sealing arrangement. In this respect, the lower portion of base rim 30 includes sidewall-to-rim transition segment 33. Transition segment 33 flares outwardly from the top of sidewall 32 and curves upwardly into base vertical sealing segment 34. Base vertical sealing segment 34 extends upwardly between sidewall-to-rim transition segment 33 and sealing platform 35. Base vertical sealing segment 34 is angled inwardly (towards the interior of container 10) to complementarily engage lid vertical sealing segment 21 when the container is sealed. Vertical sealing segment 34 and sealing platform 35 make up the sealing portion of base rim 30.

Base rim 30 also includes a tamper-resistant (anti-prying) portion located above the sealing portion. In this regard rim structure 30 further includes intermediate vertical segment 36 extending between sealing platform 35 and inwardly angled overhang segment 37. Overhang segment 37 continues on to form top vertical segment 38. Top vertical segment 38 extends upwardly, but at an outward angle to form lead-in chamfer 39. Lead-in chamfer 39 extends between top vertical segment 38 and base rim top 40. Base rim top 40 extends horizontally outwardly and then descends to form outer rim wall 41. Outer rim wall 41 extends downwardly until it meets base flange 42, which extends horizontally outward from base 25.

FIG. 9 depicts a more detailed view of circumscribed area Y of FIG. 4 showing the mechanics of engagement between the structures of lid rim 14 and base rim 30 when the container is sealed. Container 10 is sealed by placing lid 11 over base 25 and pressing lid 11 downward on base 25 so that the respective rims assume the arrangement in FIG. 9. In this regard, lid 11 is “snapped” into place and retained by and inside base 25. When sealed, vertical sealing segment 21 and flange 22 of lid 11 respectively contact base vertical sealing segment 34 and sealing platform 35 of base 25. These contacting rim surfaces impede the spillage of solid, liquids and vapors out of the sealed container.

In addition to providing protection against spillage, the sealing arrangement between the rims of the present invention container also protects against intrusion into the container by way of prying. As shown in FIGS. 6 and 9, sealing platform 35, intermediate vertical segment 36, overhang segment 37 and top vertical segment 38 form an undercut in rim structure 30. When container 10 is sealed, flange 22 drops into, and the entire lid is securely retained by, this undercut formation. Moreover, once container 10 is sealed in this fashion, the edge 24 of lid flange 22 is protected from prying instruments by the undercut formation of rim 30. Furthermore, because there is no corresponding lid structure adjacent to base flange 42, base flange 42 does not serve as a prying access point. This lack of an easily accessible pry point is in contrast to prior art containers having superposed rims with exposed rim edges.

Lid 11 further includes flange tab 60 having a tamper-evident mechanism. Flange tab 60 constitutes a localized planar extension of peripheral flange 22 that is retained by the undercut formation of rim structure 30. The accompanying figures show a preferred embodiment container having only one flange tab, but the container could be formed with a plurality of flange tabs. FIGS. 10-12 show the structure of a preferred embodiment tab 60 having tamper evident features. As shown in these figures, flange tab 60 extends outwardly from flange 22 at one corner or perimeter segment of lid 11. Flange tab 60 includes integrally formed grip tab 61, which is defined by frangible outline 62. Frangible outline 60 can be formed by way of perforations, scoring or thinning of the lid material. In the shown preferred embodiment, frangible outline 62 is formed by way of perforations. Frangible outline 62 is preferably U-shaped. Grip tab 61 includes pop-up tip portion 65 and pressing area 63. Pop-up tip 65 is located on flange tab 60 at a point distal from flange edge 24. As shown in FIG. 7, 10 an 11, pressing area 63 includes knurlments 64 to demark a visual and tactile press-down point. Flange tab 60 may include structural ribbing 71 to rigidify the tab. Grip tab 61 may similarly include such strengthening ribbing 72.

Base 25 includes localized platform extension 80 extending out from sealing platform 35. Platform 80 is positioned, shaped and adapted to complementarily receive flange tab 60 so that edge 24 is protectively received by the undercut formation of rim structure 30. Platform extension 80 connects to the structures of rim 30 in the same fashion as sealing platform 35. In this respect, platform extension 80 connects to intermediate vertical segment 36, which in turn connects to inwardly angled overhang segment 37. As shown in FIG. 11, when the container is in the sealed arrangement, flange tab 60 is engaged by the undercut structure of base rim 30 in the same manner as peripheral flange 22 is engaged by the structure of base rim 30. When flange tab 60 is engaged in this manner, flange edge 24 is protectively housed within the undercut formation of rim 30. Platform 80 may include structural ribbing 73, which in the preferred embodiment is horseshoe shaped.

Flange tab 60 includes an undercut release mechanism that provides tamper evidence. In the preferred embodiment, this undercut release mechanism comprises a grip tab 61 integrally formed in flange tab 60 by means of frangible outline 62. Frangible outline 62 is adapted to rupture when finger pressure is applied to one or more pressing areas 63 of grip tab 61 such that grip tab 61 is caused to move in a perpendicular direction relative to the surface of flange tab 60. In the preferred embodiment, pressing areas 63 of grip tab 61 are raised and platform extension 80 includes cavity 81. Inclusion of these features enhances the vertical flexing and movement of grip tab 61 relative to the horizontal surface of flange tab 60 when pressure is applied to grip tab 61. Specifically, by raising pressing areas 63 above the surface of flange tab 60 as indicated in the figures, pressing area 63 is provided with space for downward travel. Similarly, including cavity 81 in platform 80 enhances the degree of downward travel of pressing areas 63. In the sealed arrangement, flange tab 60 is in superpositional contact with platform extension 80.

The undercut release mechanism is deployed as follows. Pressing vertically downward upon pressing areas 63 causes the inner portion of grip tab 61 to descend past the surface of flange tab 60 and on into cavity 81. When pressing area 63 is caused to move downward, frangible outline 62 initially ruptures near the pressing area. This initial rupturing allows grip tab 61 to descend further relative to flange tab 60. With continued downward pressure on pressing area 63, pop-up tip 65 of grip tab 61 is pulled away from flange tab 60 until it completely separates from flange tab 60 along frangible outline 62. Ordinarily, once frangible outline 62 completely ruptures, the downward force exerted upon the pressing area causes pop-up tip 65 to rise above the flange tab surface to a point where it can be pinch-gripped by the user's thumb and index finger. In order to enhance the pop-up action of pop-up tip 65, grip tab 61 includes scored line 67, which serves as a flex point when downward pressure is applied to pressing area 63. Further, cavity 81 is preferably sized and positioned on platform 80 such that scored line 67 will be situated above distal edge 75 of cavity 80 when the container is sealed. Distal edge 75 thus acts as a fulcrum against grip tab 61 when grip tab 61 is depressed. By virtue of distal edge 75 and score line 67, when downward pressure is applied to pressing area 63 of grip tab 61, grip tab 61 will bend focally along score line 67, enhancing the pop-up action of pop-up tip 65. Should the application of pressing force upon grip tab 61 cause it to descend below flange tab 60 or not result in pop-up tip 65 of grip tab 61 reaching a point of graspability, then grip tab 61 can be pulled out from flange tab 60 and into a graspable position by applying pull-back force against knurlments 64.

As shown in FIG. 12 once grip tab 61 is in a graspable position it is deployed and can be used to extract flange tab 60 from rim 30. In this respect, deployed grip tab 61 is grasped and pulled toward the user. Pulling on grip tab 61 in this fashion causes flange tab 60 to lift and the edge 24 of flange tab 60 to point downward and move inward along platform 80 (away from the undercut formation of base rim structure 30) and towards the center of container 10. Once edge 24 of flange tab 60 is moved inwardly past top vertical segment 38 of the undercut formation of base rim 30, flange tab 60 can be pulled out from, and is released by, the undercut formation of base rim 30. Once flange tab 60 is released by base rim 30, the user can pull or push the flange tab 60 away from base 25 causing adjoining sections of peripheral flange 22 to be pulled out from the undercut formation of rim 30. Once approximately half of the lid's flange has been pulled out from the undercut structure of the base rim, lid 11 will openly separate from base 25.

The undercut release mechanism of the present invention container is adapted to distinguish between user actions that merely cause the initial partial separation of grip tab 61 from flange tab 60 and actions that indicate opening of the container. As shown in FIG. 7, flange tab 60 includes one or more further fracture lines 69 preferably emanating from frangible outline 62 and leading toward edge 24. Fracture line 69 can be formed via perforations, scoring or thinning of container material. Fracture line 69 is formed on flange tab 60 such that the force required to pull edge 24 of flange tab 60 out from the undercut formation of rim structure 30 also causes flange tab 60 to further visibly rupture along score line 69. The rupturing of fracture line 69 provides evidence that the undercut release mechanism has been utilized and the container has been opened. Additionally, once score line 69 ruptures, the subsequent application of pull force to grip tab 61 or flange tab 60 will cause flange tab 60 to twist and deform from its initial planar shape. An example of this deformation is shown in FIG. 13. Such resulting deformation provides additional evidence to the user that the container has actually been opened. By locating, extending or patterning fracture line 69 the resulting deformation to grip tab 61 or flange tab 60 can be made more prominent. For example, fracture line 69 can be shaped in accordance with FIGS. 14 a-14 d in furtherance of enhancing tamper evidence. As shown in these figures, fracture line 69 can curve away from frangible outline 62 or can be made as an extension of frangible outline 62.

The figures show only a preferred embodiment undercut release mechanism, the function of which is to effect the extraction of flange edge 24 from undercut structure of rim 30 while at the same time undergoing visible physical change. Grip tab 61 can be formed in flange tab 60 in a variety of ways such that it can be deployed and grasped. For example, FIG. 15 depicts a simpler grip tab 61 construct designed to be deployed via the application of upwardly directed finger pressure through hole 83 in platform 80. Additionally, the undercut release mechanism could be a separate element mechanically attached to, as opposed to integrally formed in, flange tab 60.

A container constructed in accordance with the present invention can be manufactured in a variety of shapes and sizes, and is preferably formed of resins or plastic materials including, but not limited to, polyethylene, polypropylene, polyvinyl chloride or polyethylene terephthalate (“PET”). The container lid and base can be transparent or translucent, and may be colored in either instance. The container can be provided with vents to promote the flow of air or steam in or out of the container. Further, the container can be of any shape, including round or polygonal. The rim structures of the container may be adapted to include a hinge such that the lid and base are connected to each other in a clamshell configuration.

Having described the invention in detail, those skilled in the art will appreciate that modifications may be made of the invention without departing from its spirit. Therefore, it is not intended that the scope of the invention be limited to the specific embodiment illustrated and described. 

1. A plastic food container comprising: a lid adapted for sealing arrangement with a base; the lid having a perimeter flange; a flange tab integrally formed in the perimeter flange; the base having a floor and a rim and a sidewall extending between the floor and the rim; the rim of the base having an undercut formation, the undercut formation being adapted to receive the perimeter flange and flange tab when the lid and base are in the sealed arrangement; the flange tab including an undercut release mechanism: the undercut release mechanism being adapted to permit a user to: a) grasp a portion of the flange tab; and b) initially open a sealed container via the extraction of the flange tab from the undercut formation by application of pulling force to the grasped portion of the flange tab; and the flange tab further including tamper evident means that provides visible indication that the undercut release mechanism has been utilized to initially open the sealed container.
 2. The food container of claim 1 wherein the undercut release mechanism is integrally formed in the flange tab.
 3. The food container of claim 1 wherein the tamper evident means includes a fracture line on the flange tab that ruptures upon utilization of the undercut release mechanism.
 4. The food container of claim 3 wherein the fracture line is located, extended or patterned on the flange tab to enhance the deformation of the flange tab when the undercut release mechanism is utilized.
 5. The food container of claim 2 wherein the undercut release mechanism is a grip tab defined by a frangible outline in the flange tab.
 6. The food container of claim 5 wherein the grip tab can be extracted from the flange tab and placed in a graspable position via the application of finger pressure within the frangible outline.
 7. The food container of claim 5 wherein the grip tab includes a pressing area formed in the grip tab and a pop-up tip, the application of downward pressure on the pressing area causing the pop-up tip to separate from the flange tab and assume a graspable position.
 8. The food container of claim 1 wherein the lid is hinged to the base. 